U.S. patent number 4,496,468 [Application Number 06/362,672] was granted by the patent office on 1985-01-29 for hydrated hydroxyethyl cellulose compositions.
This patent grant is currently assigned to NL Industries, Inc.. Invention is credited to Lonnie D. Hoover, Roy F. House.
United States Patent |
4,496,468 |
House , et al. |
* January 29, 1985 |
Hydrated hydroxyethyl cellulose compositions
Abstract
A method of activating hydroxyethyl cellulose (HEC) such that
the HEC will hydrate in heavy brines having a density greater than
about 13.5 pounds per gallon at ambient temperature, the activated
HEC compositions so produced, and viscous well servicing
compositions wherein an oleaginous liquid and a compatiblizing
agent are admixed to form a viscous slurry, admixing therewith an
aqueous solution of an inorganic salt which has an exothermic heat
of solution, and thereafter admixing HEC therewith to form a
viscous pourable composition.
Inventors: |
House; Roy F. (Houston, TX),
Hoover; Lonnie D. (Chappell Hill, TX) |
Assignee: |
NL Industries, Inc. (New York,
NY)
|
[*] Notice: |
The portion of the term of this patent
subsequent to May 18, 1999 has been disclaimed. |
Family
ID: |
23427058 |
Appl.
No.: |
06/362,672 |
Filed: |
March 29, 1982 |
Current U.S.
Class: |
507/114; 507/216;
507/926; 252/363.5; 507/925 |
Current CPC
Class: |
C08L
1/284 (20130101); C09K 8/035 (20130101); Y10S
507/926 (20130101); Y10S 507/925 (20130101) |
Current International
Class: |
C09K
8/02 (20060101); C09K 8/035 (20060101); C08L
1/28 (20060101); C08L 1/00 (20060101); C09K
007/02 (); E21B 043/00 () |
Field of
Search: |
;252/8.5A,8.5C,8.55R,363.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Natrosol, publication by Hercules, Inc., 1969, pp. 1-4 and
6-9..
|
Primary Examiner: Guynn; Herbert B.
Attorney, Agent or Firm: Browning, Bushman, Zamecki &
Anderson
Claims
We claim:
1. A viscosifying composition which will hydrate in and viscosify
heavy brines having a density greater than about 13.5 ppg at
ambient temperature which consists essentially of from about 35% to
about 55% by weight of an oleaginous liquid which is a liquid
aliphatic or aromatic hydrocarbon, from about 0.25% to about 3% by
weight based on said oleaginous liquid of a compatibilizing agent
comprising an organophilic clay, from about 15% to about 55% of an
aqueous phase comprising water and an inorganic salt which has
exothermic heat of solution wherein the concentration of said
inorganic salt is greater than about 10% by weight of said aqueous
phase, from about 10% to about 30% by weight of hydroxyethyl
cellulose, and from about 20% to about 40% by weight, based on the
weight of said organophilic clay, of a dispersant selected from the
class consisting of aliphatic alcohols having from 1 to 2 carbon
atom ketones having from 2 to 5 carbon atoms, and mixtures
thereof.
2. The composition of claim 1 containing from about 15% to about
25% by weight hydroxyethyl cellulose, from about 40% to about 50%
by weight of said oleaginous liquid, from about 25% to about 45% of
an aqueous phase comprising said water and said inorganic salt
wherein the concentration of said inorganic salt is greater than
about 20% by weight of said aqueous phase, and from about 0.5% to
about 2% by weight based on said oleaginous liquid of said
compatiblizing agent.
3. The composition of claim 1, or 3 which has been heated to a
temperature of at least about 150.degree. F.
4. The composition of claim 3 wherein said temperature results from
the solution of said inorganic salt in said water.
5. A well servicing fluid comprising a heavy brine having a density
greater than about 13.5 pounds per gallon containing a soluble salt
selected from the group consisting of calcium chloride, calcium
bromide, zinc bromide, and mixtures thereof, and a viscosifying
amount of the viscosifying composition of claim 1, 2, 3, or 4.
6. A method of activating hydroxyethyl cellulose, such that said
hydroxyethyl cellulose will hydrate in heavy brines having a
density greater than about 13.5 ppg at ambient temperatures which
comprises admixing from about 35% to about 55% of an oleaginous
liquid which is a liquid aliphatic or aromatic hydrocarbon, from
about 0.25% to about 3% by weight based on said oleaginous liquid
of a compatibilizing agent comprising an organophilic clay, and
from 20% to about 40% by weight, based on the weight of said
organophilic clay, of a dispersant selected from the class
consisting of aliphatic alcohols having from 1 to 2 carbon atom
ketones having from 2 to 5 carbon atoms, and mixtures thereof,
together to form a viscous slurry, admixing therewith from about
15% to about 55% of an aqueous phase comprising water and an
inorganic salt which has an exothermic heat of solution, wherein
the concentration of said inorganic salt is greater than about 10%
by weight of said aqueous phase, said water being added first
followed by the addition of said inorganic salt, and thereafter
admixing from about 10% to about 30% by weight hydroxyethyl
cellulose to form a viscous pourable composition.
7. The method of claim 6 wherein said viscous pourable composition
contains from about 15% to about 25% by weight hydroxyethyl
cellulose, from about 40% to about 50% by weight of said oleaginous
liquid, from about 25% to about 45% of an aqueous phase comprising
said water and said inorganic salt wherein the concentration of
said inorganic salt is greater than about 20% by weight of said
aqueous phase, and from about 0.5% to about 2% by weight based on
said oleaginous liquid of said compatiblizing agent.
8. The method of claim 6, or 7 additionally comprising heating said
viscous pourable composition to a temperature of at least
150.degree. F.
9. The method of claim 8 wherein said temperature results from the
solution of said inorganic salt in said water.
10. A well servicing fluid comprising a heavy brine having a
density greater than about 13.5 pounds per gallon containing a
soluble salt selected from the group consisting of calcium
chloride, calcium bromide, zinc bromide, and mixtures thereof and a
viscosifying amount of the viscous pourable composition prepared by
the method of claim 6, 7, 8, or 9.
Description
BACKGROUND OF THE INVENTION
In recent years, the practical operating range of clear brines for
use in the oil and gas industry has been significantly extended by
utilizing soluble zinc salts, particularly zinc bromide, so that
the advantages of clear brines can now be obtained with fluids
having densities as high as 19.2 pounds per gallon at ambient
temperatures and pressures.
The high density clear brines are used extensively: as completion
fluids to minimize plugging of perforation tunnels, to protect
formation permeability, and to minimize mechanical problems; as
workover fluids, for the same reasons; as packer fluids, to allow
easy movement and retrieval of the packer; for underreaming,
gravel-pack and sand consolidation applications; as kill fluid or
ballast fluid; for wire-line work; and as drilling fluids.
Clear brines having a density of 14.2 pounds per gallon (ppg) or
lower are generally formulated to contain sodium chloride, sodium
bromide, potassium chloride, calcium chloride, calcium bromide, or
mixtures of these salts. Clear brines having a density up to about
15.1 ppg can be formulated with calcium chloride and calcium
bromide; however, if the brine must have a low crystallization
temperature, then clear brines in this density range are generally
formulated to contain a soluble zinc salt. Zinc bromide is
preferred because brines containing it are less corrosive than
brines containing zinc chloride. Clear brines having a density
greater than about 15.1 ppg are formulated to contain zinc
bromide.
Viscous clear fluids are sometimes desired. It is known to use
hydrophilic polymeric materials such as hydroxyethyl cellulose
(HEC) as thickening agents for aqueous mediums used in such well
servicing fluids. However, HEC is not readily hydrated, solvated or
dispersed in aqueous systems having a density greater than about
13.5 pounds per gallon without elevated temperatures and/or mixing
under high shear for extended periods of time. For example,
hydroxyethyl cellulose polymers are poorly hydrated, solvated or
dispersed in such aqueous solutions containing one or more
multivalent cation water soluble salts, such as heavy brines which
are commonly used in well servicing fluids. In many cases, as for
example in workover operations, the equipment available for
preparing the well servicing fluids does not readily lend itself to
high temperature, high shear mixing. Accordingly, it is usually
necessary, if it is desired to use such thickened brines to prepare
them off the well site. Moreover, HEC is generally considered as
unsatisfactory and ineffective in heavy brines containing zinc
bromide.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide
new, polymeric compositions useful for thickening aqueous mediums,
especially heavy brines having a density greater than about 13.5
pounds per gallon.
A further object of the present invention is to provide an
improved, aqueous well servicing fluid.
Still another object of the present invention is to provide a
liquid polymeric composition which is pourable and pumpable, easily
handled and which can be used to form viscous aqueous well
servicing fluids under conditions of low shear mixing.
The above and other objects of the present invention will become
apparent from the description given herein and the appended
claims.
In accordance with the present invention, there is provided, in one
embodiment, an HEC composition for use in viscosifying aqueous
liquids comprising HEC, an oleaginous liquid, water, an inorganic
salt which has an exothermic heat of solution, and a compatiblizing
agent.
In another embodiment of the present invention, there is provided a
method of activating HEC such that the HEC will hydrate in heavy
brines having a density greater than about 13.5 ppg at ambient
temperatures which comprises admixing an oleaginous liquid and a
compatiblizing agent together to form a viscous slurry, admixing
therewith an aqueous solution of an inorganic salt which has an
exothermic heat of solution to form an emulsion, and thereafter
admixing HEC to form a viscous pourable composition.
Still another embodiment of the present invention is to provide
viscous well servicing fluids comprising a heavy brine solution
having a density greater than about 13.5 ppg and a viscosifying
amount of the HEC composition of this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The novel, liquid polymer containing compositions of the present
invention utilize hydroxyethyl cellulose (HEC) as the primary
component to effect thickening of aqueous liquids. Hydroxyethyl
cellulose is a high yield, water soluble nonionic polymer produced
by treating cellulose with sodium hydroxide followed by reaction
with ethylene oxide. Each anhydroglucose unit in the cellulose
molecule has three reactive hydroxy groups. The average number of
moles of ethylene oxide that become attached to each anhydroglucose
unit in cellulose is called moles of substituent combined. In
general, the greater the degree of substitution, the greater the
water solubility. While HEC having a mole substitution level as low
as 1.5 can be used, it is preferable to use HEC having a mole
substitution level of 1.8 or greater, especially 2.5 and greater.
It will be understood that the particular HEC chosen will depend
upon the type of liquid polymer composition, and ultimately the
type of well drilling or treating fluid, desired. For example, so
called surface treated HEC such as described in U.S. Pat. Nos.
3,455,714; 2,879,268 and 3,072,035 can be used with advantage. Such
surface treated HEC exhibits greater dispersability in the
composition. The HEC will be present in the liquid polymer
containing composition in amounts from about 10 to about 30% by
weight, based on the total liquid, polymer containing composition,
and more preferably, from about 15 to about 25% by weight, based on
the total liquid, polymer containing composition.
The oleaginous liquid used in preparing the compositions of the
present invention, in general, is any hydrophobic liquid which does
not cause significant swelling or thickening of the HEC. Exemplary
oleaginous liquids include liquid aliphatic and aromatic
hydrocarbons, particularly those containing 5 to 10 carbon atoms,
diesel oil, kerosene, petroleum distillates, petroleum oils and the
like. Generally speaking, the oleaginous liquid will be non-polar
and have a low pour point. The oleaginous liquid will be present in
the composition of the present invention in amounts from about 35
to about 55% by weight, based on the total weight of the
composition, and preferably from about 40 to about 50% by weight,
based on the total weight of the composition.
The liquid, polymer containing compositions of the present
invention also contain a compatiblizing agent for effecting
gelation or thickening of the hydrophobic liquid, emulsification of
the aqueous phase, and compatiblizing of the HEC with the
composition.
Non-limiting examples of compatiblizing agents include organophilic
hectorites, organophilic attapulgites, organophilic sepiolites, and
the like. Such organophilic clays are produced by methods and have
a composition described in U.S. Pat. Nos. 2,966,506 and 4,105,578,
both of which are herein incorporated by reference for all
purposes. In addition, the compatibilizing agent can include finely
divided siliceous materials such as fumed silica, surface treated
silicas such as silane treated silicas, etc. Particularly preferred
compatibilizing agents are the organophilic clays described in U.S.
Pat. No. 4,105,578, incorporated herein for all purposes. Such
clays are formed by the reaction of a methylbenzyl dialkyl ammonium
compound, wherein the ammonium compound contains 20 to 25% alkyl
groups having 16 carbon atoms and 60 to 75% alkyl groups having 18
carbon atoms, and a smectite-clay having a cationic exchange
capacity of at least 75 milliequivalents per hundred grams of said
clay, and wherein the amount of said ammonium compound is from
about 100 to about 120 milliequivalents per hundred grams of said
clay, 100% active clay basis. Non-limiting examples of such
preferred organophilic clays include dimethyl dialkyl ammonium
bentonite, dimethyl benzyl alkyl ammonium betonite, methyl benzyl
dialkyl ammonium bentonite, and mixtures thereof, wherein the alkyl
group contains at least 12 carbon atoms, preferably 16 to 18 carbon
atoms, and most preferably wherein the alkyl group is derived from
hydrogenated tallow. An especially preferred organophilic clay is
methyl benzyl dihydrogenated tallow ammonium bentonite.
When an organophilic clay is used as the compatiblizing agent, it
is preferable to use a dispersant to enhance the dispersability of
the organophilic clay in the oleaginous liquid. Generally speaking,
the dispersant is a low molecular weight, polar organic compound
such as a lower molecular weight alcohol, a lower ketone, a lower
alkylene carbonate and the like. Preferred are aliphatic alcohols
having from 1 to 2 carbon atoms, ketones having from 2 to 5 carbon
atoms, and mixtures thereof. Mixtures of such polar organic
compounds and water can be used as well as water itself, the latter
if sufficient shear is utilized to disperse the compatiblizing
agent. A preferred dispersant comprises a methanol-water mixture
containing from about 75 to about 98% by weight methanol and from
about 25 to about 2% by weight water. The dispersant will be
present in an amount of about 1.5 to about 100% by weight, based on
the weight of the organophilic clay, more preferably from about 20
to about 40% by weight, based on the weight of the organophilic
clay.
The compatiblizing agent will be present in the composition in
amounts of from about 0.25% to about 3% by weight, based on the
weight of the oleaginous liquid, preferably from about 0.5 to about
2% by weight, based on the weight of the oleaginous liquid.
The inorganic salt used in preparing the HEC compositions of this
invention is any water soluble salt which has an exothermic heat of
solution upon mixing the salt with water. The inorganic salt should
be compatible with the aqueous liquid to which the HEC composition
is to be added. Preferred inorganic salts are selected from the
group consisting of calcium chloride, calcium bromide, zinc
bromide, and mixtures thereof. Most preferably, the inorganic salt
will be calcium chloride, calcium bromide, or a mixture thereof.
The inorganic salt should be present in an amount greater than
about 10% by weight of the aqueous phase (water plus inorganic
salt), preferably greater than about 20% by weight of the aqueous
phase, up to a maximum concentration which forms a saturated
solution in the aqueous phase. Thus, for calcium chloride the
maximum concentration is about 37% and for calcium bromide about
55%.
The concentration of water in the HEC composition of this invention
will be such that the aqueous phase of the composition comprises
from about 15% to about 55% of the composition, preferably from
about 25% to about 45% of the composition.
In preparing the liquid, polymer containing compositions, it is
generally desirable to admix the compatiblizing agent and the
oleaginous liquid followed by addition of the dispersant under
suitable mixing conditions until the desired viscosity is achieved.
The aqueous phase is then added followed by the addition of the
HEC. The composition is then thoroughly mixed, with shear, until
the desired viscosity is achieved. The water and inorganic salt are
preferably added separately, the water being added first followed
by addition of the inorganic salt. In this manner the exothermic
heat of solution of the salt raises the temperature of the HEC
composition, preferably to a temperature greater than about
150.degree. F. If the water and inorganic salt are not added
separately, then it is desirable to heat the HEC composition to a
temperature of at least 150.degree. F. in order to best activate
the HEC for use in heavy brines.
As noted, the composition of the present invention can be mixed
with aqueous systems to provide highly useful well drilling and
treating fluids. While the aqueous medium can comprise fresh water,
preferably the aqueous medium will be one which contains a soluble
salt such as for example a soluble salt of an alkali metal, an
alkaline earth metal, a Group IB metal, a Group IIB metal, as well
as water soluble salts of ammonia and other anions. In particular,
oil field brines containing sodium chloride and/or calcium
chloride, when admixed with the compositions herein, make excellent
workover fluids. The amount of the water soluble salt dissolved in
the aqueous medium will vary depending upon the desired density of
the well drilling or treating fluid. However, it is common to
employ saturated solutions of sodium chloride and/or calcium
chloride in preparing such fluids. In preparing aqueous well
drilling and treating fluids using the liquid, polymer containing
compositions, the amount of the liquid polymer composition added
will vary depending upon the viscosity desired. Desirable well
drilling and treating fluids can be made by combining an aqueous
medium with sufficient liquid, polymer containing composition such
that the final mixture contains from about 0.1 to about 2 pounds
per barrel (ppb) of HEC.
It is another embodiment of this invention to utilize the HEC
composition of this invention to viscosify heavy brines having a
density greater than about 13.5 ppg. Such brines are particularly
difficult to viscosify at ambient temperatures with HEC, if at
all.
The heavy brines for use in the present invention contain two or
more soluble salts selected from the group consisting of calcium
chloride, calcium bromide, zinc bromide, and mixtures thereof.
Brines containing only calcium chloride can be formulated having a
density from 8.5 to about 11.7 pounds per gallon (ppg). Brines
containing only calcium bromide can be formulated having a density
from 8.5 to about 14.2 ppg. However, because calcium chloride is
much less expensive than calcium bromide, brines in the density
range from about 11.3 to about 15.1 ppg are generally formulated to
contain both calcium chloride and calcium bromide, depending on the
lowest temperature at which the brine will be used. Brines heavier
than about 15.0 ppg are generally formulated to contain calcium
chloride, calcium bromide, and zinc bromide, or only calcium
bromide and zinc bromide depending on the lowest temperature at
which the brine will be used. Brines in the density range from 14.2
ppg to 15.0 ppg may be formulated to contain calcium chloride,
calcium bromide, and zinc bromide if brines having a lower
crystallization point are desired.
The most difficult brines to viscosify contain zinc bromide, and
these brines are preferred for use in the present invention. As
indicated, such brines will have a density from about 14.2 to about
19.2 ppg.
Generally, brines of any density within the ranges disclosed are
prepared by mixing together various standard, commercially
available brines, as follows: calcium chloride brines having a
density in the range from about 11.0 to about 11.6 ppg; calcium
bromide brine having a density of 14.2 ppg; and a calcium
bromide/zinc bromide brine having a density of 19.2 ppg containing
about 20% calcium bromide and about 57% zinc bromide. Solid
anhydrous calcium chloride and solid calcium bromide are also used
in conjunction with these brines to prepare the heavy brines for
use in this invention. Standard brine mixing tables are available
from the various manufacturers of these brines.
The brines which contain zinc bromide must contain at least 20% by
weight zinc bromide as disclosed in our copending patent
application Ser. No. 161,444 filed June 20, 1980, incorporated
herein by reference for all purposes.
To further illustrate the invention, the following nonlimiting
examples are presented.
EXAMPLE 1
HEC compositions were prepared by the following procedure:
(1) A stock mixture of diesel oil and methyl benzyl dihydrogenated
tallow ammonium bentonite was prepared by mixing 300 grams of
diesel oil with 30 grams of GELTONE II for 15 minutes on a
Multimixer;
(2) The amount of this stock mixture indicated in Table 1 was added
to the amount of diesel oil indicated in this table and mixed for 2
minutes on a Multimixer;
(3) The amount of a 95/5 (weight ratio) mixture of methanol and
water indicated in Table 1 was added and mixed for 5 minutes on a
Multimixer;
(4) The amount of water indicated in Table 1 was added and mixed 5
minutes on a Multimixer;
(5) The amount of 95% CaCl.sub.2 indicated in Table 1 was added and
mixed 2 minutes on a Multimixer; and
(6) The amount of NATROSOL 250 HHR hydroxyethyl cellulose indicated
in Table 1 was added and mixed 20 minutes on a Multimixer.
The samples were evaluated at a concentration of 1 ppb HEC in a
16.0 ppg CaBr.sub.2 /ZnBr.sub.2 solution. The solutions were hand
shaken for about 30 seconds, placed on a Fann VG rheometer at 300
rpm, and the dial reading taken after 1 and 2 hours, after rolling
overnight at room temperature, and after rolling overnight at
150.degree. F. The data obtained are given in Table 2.
TABLE 1 ______________________________________ Sample Mark A B C
______________________________________ Diesel Oil 160 152.5 145
Stock Mixture 16.5 24.5 33 95/5 CH.sub.3 OH/H.sub.2 O 1.5 2.25 3
Water 102.6 102.6 102.6 95% CaCl.sub.2 47.4 47.4 47.4 HEC 75 75 75
______________________________________
TABLE 2 ______________________________________ Sample Mark A B C
______________________________________ % HEC 18.6 18.5 18.5 % Water
25.5 25.4 25.3 % CaCl.sub.2 (95%) 11.8 11.7 11.7 % Gelled Diesel
Oil (GDO) 44.2 44.4 44.6 % GELTONE II in GDO 0.84 1.25 1.66 300 rpm
Fann Dial Reading in 16.0 ppg Solution ppg HEC 1 1 1 Initial 10 10
10 1 Hour 54 63 60 2 Hours 64 73 70 After Rolling @ R.T. 64 70 70
After Rolling @ 150.degree. F. 72 79 78
______________________________________
EXAMPLE 2
HEC compositions were prepared by the following procedure:
(1) A stock mixture of diesel oil and methyl benzyl dihydrogenated
tallow ammonium bentonite was prepared by mixing together with a
Premier Dispersator for 20 minutes, 8000 parts by weight of diesel
oil, 160 parts by weight of GELTONE II organophilic bentonite, and
45.5 parts by weight of a 95/5 (weight ratio) mixture of methanol
and water, the latter functioning as a dispersion aid for the
organophilic clay;
(2) To 150 gm of this gelled diesel oil were added 130.9 gm of
water and this was mixed for two minutes on a Multimixer;
(3) 19.1 gm of 78% CaCl.sub.2 were added and mixed three
minutes;
(4) 75 gm of NATROSOL 250 HHR were added. Thickened immediately on
mixing. An additional 50 gm of gelled diesel oil were added. Mixed
10 minutes on a Multimixer. Designated Sample D.
(5) Sample E. Prepared as above except used 111.6 gm water, 38.4 gm
of 78% CaCl.sub.2, and 25 gm additional gelled diesel.
(6) Sample F. prepared as (5) except used 92.3 gm water and 57.7 gm
of 78% CaCl.sub.2.
(7) Sample G. Prepared as (5) except used 73 gm water and 77 gm 78%
CaCl.sub.2.
(8) Sample H. Prepared as (5) except that 102.7 gm of water and
47.3 gm of 95% CaCl.sub.2 was used.
(9) A portion of samples D, E, F, and G were heated at 150.degree.
F. overnight.
These samples were evaluated at a concentration of 1 ppb HEC in a
16.0 ppg CaBr.sub.2 /ZnBr.sub.2 solution and/or a 19.2 ppg
ZnBr.sub.2 solution. The solutions were hand shaken for about 30
seconds, placed on a Fann VG rheometer at 300 rpm, and the dial
readings taken periodically as indicated in Table 3.
The data obtained, given in Table 3, indicate that the CaCl.sub.2
content of the aqueous phase should preferably be greater than
about 20%. Heating the samples containing 10% and 20% CaCl.sub.2 in
the aqueous phase did not improve their rate of hydration in the
19.2 ppg brine.
EXAMPLE 3
Sample I was prepared by adding 10 gm of NATROSOL 250 HHR to 20 gm
of the gelled diesel oil of Example 2 and thereafter adding 20 gm
of a 14.2 ppg CaBr.sub.2 solution. Shaken by hand for mixing.
Sample J was prepared by mixing together 150 gm of gelled diesel
oil and 62.6 gm of water with a Multimixer, adding 72.0 gm of 91%
CaBr.sub.2, and adding 75 gm of HEC. Mixed with Multimixer.
Sample K was prepared on Sample J except that the water and
CaBr.sub.2 were mixed and cooled to room temperature being adding
this solution to the gelled diesel oil, followed by the HEC.
A portion of samples J and K were heated at 150.degree. F.
overnight.
The samples were evaluated in the same manner as in Example 3.
The data obtained, given in Table 4, indicate that a good rate of
hydration can be obtained in the 16.0 ppg brine and a fair rate of
hydration in the 19.2 ppg brine, provided that the samples are
prepared by the preferred process which utilizes dry inorganic salt
rather than an inorganic salt solution. The latter HEC composition,
sample K, was inferior to sample J prepared using dry powder
CaBr.sub.2. Heating sample K does increase the rate of hydration of
the sample, however.
TABLE 3 ______________________________________ Sample Mark D E F G
H ______________________________________ % HEC 17.65 18.75 18.75
18.75 18.75 % Water 30.8 27.9 23.1 18.25 23.1 % CaCl.sub.2 4.5 9.6
14.4 19.25 14.4 (78%) % Gelled 47.05 43.75 43.75 43.75 43.75 Diesel
Oil Temperature, 120-150* 135-150* 150-150* 155-150* 170 .degree.F.
300 rpm Fann Dial Reading in 16.0 ppg Solution ppb HEC 1 1 1 1 1
Initial 9 8 8 8 8 10 Minutes 12 11 16 18 17.5 20 Minutes 15 17 24
29 29.5 30 Minutes 18 23 32 40 39 1 Hour 23 38 54 59 60 2 Hours --
-- -- -- 69.5 After Rolling 70 68 70 72 74 @ 150.degree. F. 300 rpm
Fann Dial Reading in 19.2 ppg Solution ppb HEC 1--1 1--1 1--1 1--1
1 Initial 21-22 21-22 21-22 21-22 22 10 Minutes 25 -- 24 -- 33 --
36 -- -- 20 Minutes 30 -- -- -- 52 -- 50 -- -- 30 Minutes 36-27.5
43-36.5 74-76.5 71-81 80 1 Hour 48 -- 69 -- 108-110 109-114 116 2
Hours -- -- -- -- -- -- -- -- 124.5 24 Hours -- -- -- -- -- -- --
-- -- After Rolling 128-107 123-128 127-129 126-133 128 @
150.degree. F. ______________________________________ *Sample
rolled 20 hours @ 150.degree. F.
TABLE 4 ______________________________________ Sample Mark I J J J
K K ______________________________________ % HEC 20 20.85 20.85 %
Water * 17.4 17.4 % CaBr.sub.2 (91%) * 20.0 20.0 % Gelled Diesel
Oil 40 41.75 41.75 300 rpm Fann Dial Reading in 16.0 ppg Solution
ppb HEC 1 1.sup.1 1.sup.2 1.sup.3 1.sup.1 1.sup.3 Initial 8 8 8 8 8
10 Minutes 15 12.5 -- -- -- -- 20 Minutes 24 20 -- -- -- -- 30
Minutes 28 27.5 -- -- -- -- 1 Hour 36 40 -- 43 -- 33 2 Hours 48
53.5 65 65 26 52 24 Hours 53 66 -- 76 -- 61 After Rolling @
150.degree. F. 69 76 77 75 67 60 300 rpm Fann Dial Reading in 19.2
ppg Solution ppb HEC 1 1 -- -- -- -- Initial 22 21.5 -- -- -- -- 10
Minutes 24 27 -- -- -- -- 20 Minutes 30 -- -- -- -- -- 30 Minutes
37 55 -- -- -- -- 1 Hour 76 86 -- -- -- -- 2 Hours -- -- -- -- --
-- 24 Hours -- 130 -- -- -- -- After Rolling @ 150.degree. F. 122
-- -- -- -- -- ______________________________________ *Contains 40%
of a 14.2 ppg CaBr.sub.2 solution .sup.1 Sample set for 16 hours
before testing. .sup.2 Sample set for several days testing. .sup.3
Sample heated at 150.degree. F. overnight before testing.
* * * * *